The accident happened just before 2:30 p.m. on the southbound lanes of Interstate 90/94 -- the Dan Ryan Expressway -- between 69th and 70th streets and involved a motorcycle and a car, police said.

Police, citing preliminary information, said a red 2007 Pontiac Coupe was attempting to make an abrupt lane change to avoid missing the exit at 71st Street, cutting off the motorcycle in an adjacent lane.

Rodriguez was unable to avoid the car and collided with it. He was transported to an area hospital where he was pronounced dead.

"The impact happened so quick and it was just a chain of events," said witness Larry Brown. "[The officer] didn't have a helmet on. He didn't have anything on, nothing but his shirt."

The driver of the Pontiac, 50-year-old Dennis Anderson, was charged with improper lane usage and no valid insurance, police said.